Hi, On 2023-06-27 16:40:08 +1200, Thomas Munro wrote: > On Tue, Jun 27, 2023 at 4:32 PM Peter Geoghegan <p...@bowt.ie> wrote: > > On Mon, Jun 26, 2023 at 9:09 PM Andres Freund <and...@anarazel.de> wrote: > > > I think we should be able to have a post-check that can figure out > > > if the copied root page is out of date after searching it, without > > > needing the > > > content lock. > > > > I'm guessing that you're thinking of doing something with the page LSN?
Yes, that seems to be the most obvious. > If the goal is to get rid of both pins and content locks, LSN isn't > enough. I was imaginging you'd have a long-lived pin. I don't think trying to make it work without that is particularly promising in this context, where it seems quite feasible to keep pins around for a while. > A page might be evicted and replaced by another page that has the same LSN > because they were modified by the same record. Maybe that's vanishingly > rare, but the correct thing would be counter that goes up on modification > AND eviction. I don't think it would need to be a single counter. If we wanted to do something like this, I think you'd have to have a counter in the buffer desc that's incremented whenever the page is replaced. Plus the LSN for the page content change "counter". Greetings, Andres Freund
